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At least 1,477 records · Page 82Linked to original sources
USGS2014

Digital topographic data based on lidar survey of Mount Shasta Volcano, California, July-September 2010

The most voluminous of the Cascade volcanoes, northern California’s Mount Shasta, is a massive compound stratovolcano composed of at least four main edifices constructed over a period of at least 590,000 years. An ancestral Shasta volcano was destroyed by Earth’s largest known Quaternary subaerial debris avalanche, which filled Shasta Valley, northwest of the volcano. The Hotlum cone, forming the present summit, the Shastina lava dome complex, and the Black Butte lava dome on the southwest flank, were constructed during the early Holocene. As part of the American Recovery and Reinvestment Act (ARRA) of 2009, the U.S. Geological Survey was awarded funding for high-precision airborne lidar (light detection and ranging) data collection at several volcanoes in the Cascade Range. Data collection was arranged by the Oregon Lidar Consortium, administered by the Oregon Department of Geology and Mineral Industries (DOGAMI). The Oregon Lidar Consortium contracted with Watershed Sciences, Inc., to collect 1,220 square km of high-precision airborne lidar data. These data provide a digital map of the ground surface beneath forest cover with horizontal resolution of 1 m (average of 1.82 ground laser returns per square meter) and estimated vertical accuracy of ±4 centimeters (1 sigma), and horizontal accuracies of ±1.5 centimeters. These data will contribute to monitoring and description of natural hazards, the study of regional geology and volcanic landforms, and analysis of landscape modification during and after the next volcanic eruption at Mount Shasta. Survey Bounding Coordinates: West Bounding Coordinate: −122.438774 East Bounding Coordinate: −121.888382 North Bounding Coordinate: 41.564495 South Bounding Coordinate: 41.126339

California↗
USGS2011

Gently dipping normal faults identified with Space Shuttle radar topography data in central Sulawesi, Indonesia, and some implications for fault mechanics

Space-shuttle radar topography data from central Sulawesi, Indonesia, reveal two corrugated, domal landforms, covering hundreds to thousands of square kilometers, that are bounded to the north by an abrupt transition to typical hilly to mountainous topography. These domal landforms are readily interpreted as metamorphic core complexes, an interpretation consistent with a single previous field study, and the abrupt northward transition in topographic style is interpreted as marking the trace of two extensional detachment faults that are active or were recently active. Fault dip, as determined by the slope of exhumed fault footwalls, ranges from 4° to 18°. Application of critical-taper theory to fault dip and hanging-wall surface slope, and to similar data from several other active or recently active core complexes, suggests a theoretical limit of three degrees for detachment-fault dip. This result appears to conflict with the dearth of seismological evidence for slip on faults dipping less than ~ 30°. The convex-upward form of the gently dipping fault footwalls, however, allows for greater fault dip at depths of earthquake initiation and dominant energy release. Thus, there may be no conflict between seismological and mapping studies for this class of faults.

Sulawesi↗
USGS2005

Shelf-edge deltas and drowned barrier-island complexes on the northwest Florida outer continental shelf

A high-resolution multibeam survey of the northwest Florida shelf mapped six relict shelf-edge deltas, each with a drowned barrier-island system developed on its south and southwestern rims. The deltas appear to have formed during periods of sea-level stasis that occurred between 58,000 and 28,000 years ago. The barrier islands formed on the deltas during periods of slow regression during this same time interval. Large fields of asymmetric dunes are found on the delta surfaces as well as on the south and southwestern flanks of the deltas. The asymmetry and orientation of the dunes suggest that a northward-flowing current was sheared by the presence of the delta topography, and as a result, the upper layer of the flow continued to the north, whereas the lower layer was steered by the topography. The topographic steering accelerated the northward flow around the south and southwestern flanks with speeds adequate to form large dunes. The flow slowed after rounding southwestern flank but accelerated again as it encountered the next delta flank to the north. The age of the dune formation is unknown, and no northward-flowing geostrophic flow has been reported in the literature from this area. ?? 2004 Elsevier B.V. All rights reserved.

Geomorphology↗
USGS1971

The vertical gradient of gravity in vertical and near vertical boreholes

The vertical gradient of gravity is the rate of change of gravity in the direction of the plumb line. For a vertical borehole interval, it is approximated by the ratio of the gravity difference to the height difference as measured between the end points of the interval. The borehole vertical gradient is strongly affected by the densities of the rocks laterally adjacent to the well. Because of this useful effect, vertical (gravimetric) density profiles of the rooks adjacent to the borehole can be calculated from the borehole vertical gradients. A second useful effect, termed the "anomalous" vertical gradient, is caused by non-level equal-density surfaces related to the local and regional geology. The anomalous vertical gradient can enhance exploration beyond the confines of the borehole although it is a small and commonly negligible effect. These two useful effects are not determinable with absolute accuracy from observed borehole vertical gradients without independent subsurface rock density and (or) surface gravity information. In this study observed vertical gradients from high-precision, detailed gravity surveys made in seven shallow oil wells that penetrate a late Cenozoic sequence of marine and non-marine rocks in the Midway-Sunset Oil Field, California, are interpreted to obtain vertical density profiles. These gravimetric density profiles are adjusted 1) for anomalous vertical gradients calculated from surface gravity maps end, alternatively, measured on a portable tower and 2) for small extraneous effects of surface topography. The unadjusted and adjusted density profiles are compared with density measurements of core samples. The unadjusted density profiles of six wells are on the average systematically greater than core densities by .05 g/cm 3 . Adjusted profiles for the same wells agree with core densities to within .01 g/cm 3 on the average. Densities of an adjusted profile of a seventh well are .15 g/cm 3 less than those of the unadjusted profile and are in better agreement with core densities by that amount. However, residual systematic discrepancies between core and gravimetric densities for this seventh well indicate a measurable variation of the anomalous vertical gradient with depth and (or) lack of representative core density data. Topographic effects and anomalous vertical gradients in boreholes are usually small and change slowly with depth but, in some instances, may be comparatively large and change rapidly with depth. In the former case, gravimetric density profiles unadjusted for these effects can be in error by as much as about .05 g/cm 3 and, in the latter case, by as much as several tenths of a g/cm 3 . In both cases, relative errors between neighboring parts of the density profiles are much smaller. In cases where the anomalous vertical gradient changes appreciably with depth, it cannot be reliably estimated in the borehole from surface gravity measurements or from tower gradient measurements, which are especially sensitive to very shallow local density irregularities. At any borehole depth the anomalous gradient can be estimated from the difference between core and gravimetric densities of the same borehole interval. The core densities must be highly accurate and representative of the interval and the gravimetric density must he adjusted for topographic effects. Measured borehole vertical gradients have precisions of .00025 to .00050 mgal/ft (8 to 16 Eotvos units) for vertical intervals as small as 10 feet (3 meters); this meets the most stringent requirements of recognized applications for borehole gravimetry. An ideal borehole density logging device would be an in-motion continuously recording vertical gravity gradiometer.

Open-File Report↗
USGS2026

Channel morphology and large wood control postfire debris-flow erosion and deposition

Runoff-generated debris flows are a known response to wildfire, and accurately predicting the volume of these debris flows is important for estimating the magnitude of downstream hazards. Prior data collection efforts have focused on debris-flow volume measurements at catchment outlets, but few studies have considered how erosion and deposition modulate the volume of sediment arriving at catchment outlets. This study takes advantage of a high-resolution dataset to document the factors that control the total debris-flow volume reaching the catchment outlet during a fatal postfire debris flow. Using pre- and post-event airborne lidar, satellite imagery and field mapping, we found that a postfire debris flow in the Black Hollow catchment in northern Colorado eroded 136,000 ± 30,000 m 3 and redeposited 27,000 ± 7,500 m 3 in the main channel. Most of the in-channel deposition (52% by volume) occurred where a confined channel reach transitioned to an unconfined channel reach downstream, allowing the flow to widen and deposit material. Wood jams played multiple roles in the debris-flow dynamics, both nucleating deposition (25% of the deposit volume was stored behind wood jams) and exacerbating erosion (50% of the total erosion occurred downstream from a wood dam break). The remaining deposition occurred due to spatial changes in channel slope as well as deposition observed at newly formed channel bars. Using these data in this study, we identified topographic and vegetation metrics that can be used (pre-event) to anticipate where deposition may occur in channels prior to a debris flow.

Colorado↗
USGS2007

Mapping the invasive species, Chinese tallow, with EO1 satellite Hyperion hyperspectral image data and relating tallow occurrences to a classified Landsat Thematic Mapper land cover map

Our objective was to provide a realistic and accurate representation of the spatial distribution of Chinese tallow (Triadica sebifera) in the Earth Observing 1 (EO1) Hyperion hyperspectral image coverage by using methods designed and tested in previous studies. We transformed, corrected, and normalized Hyperion reflectance image data into composition images with a subpixel extraction model. Composition images were related to green vegetation, senescent foliage and senescing cypress-tupelo forest, senescing Chinese tallow with red leaves ('red tallow'), and a composition image that only corresponded slightly to yellowing vegetation. These statistical and visual comparisons confirmed a successful portrayal of landscape features at the time of the Hyperion image collection. These landscape features were amalgamated in the Landsat Thematic Mapper (TM) pixel, thereby preventing the detection of Chinese tallow occurrences in the Landsat TM classification. With the occurrence in percentage of red tallow (as a surrogate for Chinese tallow) per pixel mapped, we were able to link dominant land covers generated with Landsat TM image data to Chinese tallow occurrences as a first step toward determining the sensitivity and susceptibility of various land covers to tallow establishment. Results suggested that the highest occurrences and widest distribution of red tallow were (1) apparent in disturbed or more open canopy woody wetland deciduous forests (including cypress-tupelo forests), upland woody land evergreen forests (dominantly pines and seedling plantations), and upland woody land deciduous and mixed forests; (2) scattered throughout the fallow fields or located along fence rows separating active and non-active cultivated and grazing fields, (3) found along levees lining the ubiquitous canals within the marsh and on the cheniers near the coastline; and (4) present within the coastal marsh located on the numerous topographic highs. ?? 2005 US Government.

International Journal of Remote Sensing↗
USGS2022

Climate refugia for Pinus spp. in topographic and bioclimatic environments of the Madrean sky islands of México and the United States

Climate refugia, or places where habitats are expected to remain relatively buffered from regional climate extremes, provide an important focus for science and conservation planning. Within high-priority, multi-jurisdictional landscapes like the Madrean sky islands of the United States and México, efforts to identify and manage climate refugia are hindered by the lack of high-quality and consistent transboundary datasets. To fill these data gaps, we assembled a bi-national field dataset ( n = 1416) for five pine species ( Pinus spp.) and used generalized boosted regression to model pine habitats in relation to topographic variability as a basis for identifying potential microrefugia at local scales in the context of current species’ distribution patterns. We developed additional models to quantify climatic refugial attributes using coarse scale bioclimatic variables and finer scale seasonal remote sensing indices. Terrain metrics including ruggedness, slope position, and aspect defined microrefugia for pines within elevation ranges preferred by each species. Response to bioclimatic variables indicated that small shifts in climate were important to some species (e.g., P. chihuahuana, P. strobiformis ), but others exhibited a broader tolerance (e.g., P. arizonica ). Response to seasonal climate was particularly important in modeling microrefugia for species with open canopy structure and where regular fires occur (e.g., P. engelmannii and P. chihuahuana ). Hotspots of microrefugia differed among species and were either limited to northern islands or occurred across central or southern latitudes. Mapping and validation of refugia and their ecological functions are necessary steps in developing regional conservation strategies that cross jurisdictional boundaries. A salient application will be incorporation of climate refugia in management of fire to restore and maintain pine ecology.

Arizona, Chihuahua, New Mexico, Sonora↗
USGS1978

Analyses of rocks and stream sediments of the Superstition Wilderness, Arizona

The geochemical investigation of the Superstition Wilderness, Maricopa, Pinal and Gila Counties, Arizona, consisted of the collection and analyses of 2269 samples. This included 1231 rocks and 1038 stream sediments. All samples were prepared and analyzed on location during two separate field seasons (fall of 1975 and 1976) by mobile laboratories of the U.S. Geological Survey. Sample localities and analytical results are listed in this report. Samples lie within the following U.S.G.S. topographic quadrangles: Goldfield, Mormon Flat Dam, Weavers Needle, Horse Mesa Dam, Iron Mountain, Pinyon Mountain, Haunted Canyon, and Two Bar Mountain. Locations for all samples are in Universal Transverse Mercator (UTM) coordinates, the X coordinate is the northing value, which ranges from 3,693,000 m to 3,720,000 m and the Y coordinate is the casting value, which ranges from 453,500 m to 500,000 m. Because of limitations of the computer program, the initial digit of the northing numbers has been dropped. Data of rocks are listed on Table 1 and stream sediments on Table 2. The analytical and geologic data were entered into a computer storage system (RASS II) by S. K. McDanal and retrievals were handled by T. M. Billings and George VanTrump. Geochemical sampling was carried out during geologic mapping by a U.S. Geological Survey field party consisting of D. W. Peterson, D. L. Gaskill, M. L. Sorenson, and W. E. Yeend, assisted by Kerwin Stark, N. H. Suneson, and G. D. Johnpeer. Analytical support was given by R. N. Babcock and D. G. Murrey.

Arizona↗
USGS2007

Hydraulic Characteristics of Bedrock Constrictions and Evaluation of One- and Two-Dimensional Models of Flood Flow on the Big Lost River at the Idaho National Engineering and Environmental Laboratory, Idaho

A 1.9-mile reach of the Big Lost River, between the Idaho National Engineering and Environmental Laboratory (INEEL) diversion dam and the Pioneer diversion structures, was investigated to evaluate the effects of streambed erosion and bedrock constrictions on model predictions of water-surface elevations. Two one-dimensional (1-D) models, a fixed-bed surface-water flow model (HEC-RAS) and a movable-bed surface-water flow and sediment-transport model (HEC-6), were used to evaluate these effects. The results of these models were compared to the results of a two-dimensional (2-D) fixed-bed model [Transient Inundation 2-Dimensional (TRIM2D)] that had previously been used to predict water-surface elevations for peak flows with sufficient stage and stream power to erode floodplain terrain features (Holocene inset terraces referred to as BLR#6 and BLR#8) dated at 300 to 500 years old, and an unmodified Pleistocene surface (referred to as the saddle area) dated at 10,000 years old; and to extend the period of record at the Big Lost River streamflow-gaging station near Arco for flood-frequency analyses. The extended record was used to estimate the magnitude of the 100-year flood and the magnitude of floods with return periods as long as 10,000 years. In most cases, the fixed-bed TRIM2D model simulated higher water-surface elevations, shallower flow depths, higher flow velocities, and higher stream powers than the fixed-bed HEC-RAS and movable-bed HEC-6 models for the same peak flows. The HEC-RAS model required flow increases of 83 percent [100 to 183 cubic meters per second (m3/s)], and 45 percent (100 to 145 m3/s) to match TRIM2D simulations of water-surface elevations at two paleoindicator sites that were used to determine peak flows (100 m3/s) with an estimated return period of 300 to 500 years; and an increase of 13 percent (150 to 169 m3/s) to match TRIM2D water-surface elevations at the saddle area that was used to establish the peak flow (150 m3/s) of a paleoflood with a return period of 10,000 years. A field survey of the saddle area, however, indicated that the elevation of the lowest point on the saddle area was 1.2 feet higher than indicated on the 2-ft contour map that was used in the TRIM2D model. Because of this elevation discrepancy, HEC-RAS model simulations indicated that a peak flow of at least 210 m3/s would be needed to initiate flow across the 10,000-year old Pleistocene surface. HEC-6 modeling results indicated that to compensate for the effects of streambed scour, additional flow increases would be needed to match HEC-RAS and TRIM2D water-surface elevations along the upper and middle reaches of the river, and to compensate for sediment deposition, a slight decrease in flows would be needed to match HEC-RAS water-surface elevations along the lower reach of the river. Differences in simulated water-surface elevations between the TRIM2D and the HEC-RAS and HEC-6 models are attributed primarily to differences in topographic relief and to differences in the channel and floodplain geometries used in these models. Topographic differences were sufficiently large that it was not possible to isolate the effects of these differences on simulated water-surface elevations from those attributable to the effects of supercritical flow, streambed scour, and sediment deposition.

Scientific Investigations Report↗
USGS1979

Detection and mapping of hydrothermally altered rocks in the vicinity of the Comstock Lode, Virginia Range, Nevada, using enhanced Landsat images

The Virginia Range, immediately southeast of Reno, Nev., consists mainly of flows, breccias, and turfs of Miocene age. Most of these volcanic rocks are of intermediate composition; rhyodacite is the most common rock type. Basalt, rhyolite and rhyolite tuff, and tuffaceous sedimentary rocks of Miocene and Pliocene age also cover substantial areas in the range. Pre-Tertiary metasedimentary, metavolcanic, and granitic rocks are exposed in scattered inliers, mostly along the southern and eastern margins of the range. Several large areas and many small areas within the volcanic pile were subjected to hydrothermal alteration during and after the period of intermediate volcanic activity. Economic precious metal mineralization is spatially and temporally associated with the hydrothermal alteration in several areas. The most important deposit is the Comstock Lode, which produced 192 million troy ounces of silver and 8.3 million troy ounces of gold from epithermal veins (Bonham, 1969). The hydrothermally altered rocks include silicified, advanced argillic, montmorillonite-bearing argillic, and propylitic types. The first three types typically contain pyrite, and some propylitic rocks contain pyrite as well. Supergene oxidation of these pyritic rocks produces limonitic bleached rocks. The term 'limonite,' as used here, refers to any combination of the minerals hematite, goethite, and Jarosite. Where vegetation cover is sparse to moderate, these limonitic rocks are readily identified on Landsat images enhanced by the color-ratio composite technique developed by Rowan and others (1974), so the altered areas can be mapped. About 30 percent tree cover (here mainly pinyon pine) is sufficient to change the spectral signature of individual picture elements (pixels) enough so that limonitic materials can no longer be uniquely identified. As in all other areas where this technique has been applied, limonitic unaltered rocks with intermediate to high albedos have the same appearance on the color-ratio composite as limonitic altered rocks. This problem represents the most important limitation to the use of enhanced Landsat images for detection and mapping of hydrothermally altered rocks. Reflectance spectra of altered and unaltered rocks taken in the field in the Virginia Range show that most altered rocks have a conspicuous absorption band near 2.2 ?m produced by clay minerals or alunite, whereas unaltered rocks have no features in this spectral region. Thus spectral information for selected bands in the 1.1-2.5 ?m region may allow discrimination between limonitic altered and limonitic unaltered rocks (Rowan and others, 1977; Abrams and others, 1977; Rowan and Abrams, 1978). Another potential limitation is loss of spectral information on slopes with low effective sun angle. Although a minor problem in the Virginia Range, loss of information sufficient to preclude identification of limonitic altered rocks occurs with effective sun angle lower than 20-25 degrees. Thus, even at moderate latitudes substantial parts of areas with high topographic relief may be lost to observation.

Open-File Report↗
USGS2010

Lunar basin formation and highland stratigraphy

Multiring impact basins, formed after solidification of the lunar crust, account for most or all premare regional deposits and structures expressed in the lunar landscape and for major topographic and gravity variations. A fresh basin has two or more concentric mountain rings, a lineated ejecta blanket, and secondary impact craters. Crackled material on the floor may be impact melt. The ejecta blanket was emplaced at least partly as a ground‐hugging flow and was probably hot. A suggested model of basin formation is that the center lifts up and the rings form by inward collapse during evisceration. The resulting basin is shallow and has a central uplift of the mantle. This results in a central gravity high and a ring low. Later flooding by mare basalt has since modified most near side basins. Highland deposits of plains, furrowed and pitted terrain, and various hills, domes, and craters that were interpreted before the Apollo missions as being volcanic can now be interpreted as being basin related. A province map of the whole moon shows that the relatively young Orientale and Imbrium basins imprinted and rejuvenated much of the moon's surface; older basins must have also. The most primitive cratered surface remaining is mostly on the far side, distant from Imbrium and Orientale and other large relatively young basins. All five lunar landings in the highlands sampled stratigraphic units probably related to basins. Several nearly obliterated basins have been discovered recently, including a deep one on the far side that is as wide as the moon's radius. The presence of these ancient basins suggests that the surface is effectively saturated by basins and that many others were completely destroyed by later impacts. Basin impacts may have churned the lunar crust to large depths.

Reviews of Geophysics and Space Physics↗
USGS2022

Limits to coseismic landslides triggered by Cascadia Subduction Zone earthquakes

Landslides are a significant hazard and dominant feature throughout the landscape of the Pacific Northwest. However, the hazard and risk posed by coseismic landslides triggered by great Cascadia Subduction Zone (CSZ) earthquakes is highly uncertain due to a lack of local and global data. Despite a wealth of other geologic evidence for past earthquakes on the Cascadia Subduction Zone, no landslides have been definitively linked to such earthquakes, even in areas otherwise highly susceptible to failure. While shallow landslides may not leave a lasting topographical signature in the landscape, there are thousands of deep-seated landslides in Cascadia, and these deposits often persist for hundreds of years and multiple earthquake cycles. Synthesizing newly developed inventories of dated large deep-seated landslides in the Oregon Coast Range, we use statistical methods to estimate the proportion of these types of landslides that could have been triggered during past great Cascadia Subduction Zone earthquakes. Statistical analysis of high-precision dendrochronology ages of landslide-dammed lakes and surface roughness-dated bedrock landslides reveal Cascadia Subduction Zone earthquakes may have triggered 0–15 % of large deep-seated landslides in the Oregon Coast Range over multiple earthquake cycles. Our results refine estimates from previous studies and further suggest that coseismic triggering accounts for a small fraction of the total deep-seated bedrock landslides mapped in coastal Cascadia. However, if the real rate of coseismic landslide triggering during CSZ earthquakes is near our estimated upper bound for the 1700 CSZ earthquake, we estimate up to 2400 coseismic large deep-seated landslides could occur in the Oregon Coast Range in a single earthquake. These findings suggest Cascadia is consistent with global observations from other subduction zones and that coseismic landslides may still represent a serious geohazard in the region.

Oregon↗
USGS2020

Community tools for cartographic and photogrammetric processing of Mars Express HRSC images

In this chapter we describe the software we have developed for photogrammetric processing of images from the Mars Express High Resolution Stereo Camera (MEX HRSC) to produce digital topographic models (DTMs) and orthoimages, as well as testing we have performed. HRSC has returned images, including stereo and color coverage of most of Mars at decameter scales. The instrument team has developed an extremely powerful processing pipeline and delivered a large number of high-level data products, but our independent software is nevertheless of interest because it provides a check on the standard products, sheds light on the capabilities of software elements we use for multiple missions besides HRSC, and is publicly available, giving users the opportunity to make products that may not (yet) be released by the team and custom products such as local mosaics. We have tested our software on images of three areas: Candor Chasma and Nanedi Valles (both the subject of past DTM comparisons reported by Heipke et al., 2007) and Gale crater, which was extensively mapped at pixel scales 50 times finer than HRSC before its selection as the landing site of the Curiosity rover. We find the vertical precision and mean deviation from the altimetry data used as a control reference for our DTMs to be comparable to the nadir image pixel size. The horizontal resolution of the DTMs appears to be an order of magnitude coarser than the lower limit of 3–5 image pixels that is commonly stated.

Book chapter↗
USGS1994

Hydrogeology of recharge areas and water quality of the principal aquifers along the Wasatch Front and adjacent areas, Utah

The principal basin-fill aquifers in Cache Valley, the lower Bear River area, and along the Wasatch Front provide ground water to about 84 percent of the population of Utah. Recharge areas for the principal aquifers were mapped to provide information needed for the implementation of ground-water quality regulations and a State ground-water protection plan. Water samples were collected and analyzed to provide baseline water- quality data for the principal aquifers. The study area includes five subareas: Cache Valley, the 1ower Bear River area, the East Shore area, Salt Lake Valley, and Utah and Goshen Valleys. Basin-fill deposits in each subarea are lithologically heterogeneous. The principal aquifers in most of the subareas are composed of multiple discontinuous unconfined and confined aquifers and confining layers. Primary recharge areas generally are located along adjacent mountain fronts and extend into the valleys at the mouths of major drainages. Secondary recharge areas are located on the benches and uplands of the valleys. Ground-water flow generally is from these recharge areas to the discharge areas in the topographically low parts of the valleys. In general, dissolved-solids concentrations in ground water range from less than 500 mg/L to about 3,000 mg/L. Of 73 water samples, 5 contained inorganic constituents in concentrations that exceeded State of Utah water-quality standards. None of the samples contained concentrations of organic compounds that exceeded State standards.

Water-Resources Investigations Report↗
USGS2018

Managing salinity in Upper Colorado River Basin streams: Selecting catchments for sediment control efforts using watershed characteristics and random forests models

Elevated concentrations of dissolved-solids (salinity) including calcium, sodium, sulfate, and chloride, among others, in the Colorado River cause substantial problems for its water users. Previous efforts to reduce dissolved solids in upper Colorado River basin (UCRB) streams often focused on reducing suspended-sediment transport to streams, but few studies have investigated the relationship between suspended sediment and salinity, or evaluated which watershed characteristics might be associated with this relationship. Are there catchment properties that may help in identifying areas where control of suspended sediment will also reduce salinity transport to streams? A random forests classification analysis was performed on topographic, climate, land cover, geology, rock chemistry, soil, and hydrologic information in 163 UCRB catchments. Two random forests models were developed in this study: one for exploring stream and catchment characteristics associated with stream sites where dissolved solids increase with increasing suspended-sediment concentration, and the other for predicting where these sites are located in unmonitored reaches. Results of variable importance from the exploratory random forests models indicate that no simple source, geochemical process, or transport mechanism can easily explain the relationship between dissolved solids and suspended sediment concentrations at UCRB monitoring sites. Among the most important watershed characteristics in both models were measures of soil hydraulic conductivity, soil erodibility, minimum catchment elevation, catchment area, and the silt component of soil in the catchment. Predictions at key locations in the basin were combined with observations from selected monitoring sites, and presented in map-form to give a complete understanding of where catchment sediment control practices would also benefit control of dissolved solids in streams.

Upper Colorado River Basin↗
USGS2007

Late quaternary paleoseismology of the southern Steens fault zone, northern Nevada

The 192-km-long Steens fault zone is the most prominent normal fault system in the northern Basin and Range province of western North America. We use trench mapping and radiometric dating to estimate displacements and timing of the last three surface-rupturing earthquakes (E1-E3) on the southern part of the fault south of Denio, Nevada. Coseismic displacements range from 1.1 to 2.2 ?? 0.5 m, and radiometric ages indicate earthquake times of 11.5 ?? 2.0 ka (E3), 6.1 ?? 0.5 ka (E2), and 4.6 ?? 1.0 ka (E1). These data yield recurrence intervals of 5.4 ?? 2.1 k.y. between E3 and E2, 1.5 ?? 1.1 k.y. between E2 and E1, and an elapsed time of 4.6 ?? 1.0 k.y. since E1. The recurrence data yield variable interval slip rates (between 0.2 ?? 0.22 and 1.5 ?? 2.3 mm/yr), but slip rates averaged over the past ???18 k.y. (0.24 ?? 0.06 mm/year) are similar to long-term (8.5-12.5 Ma) slip rates (0.2 ?? 0.1 mm /yr) measured a few kilometers to the north. We infer from the lack of significant topographic relief across the fault in Bog Hot Valley that the fault zone is propagating southward and may now be connected with a fault at the northwestern end of the Pine Forest Range. Displacements documented in the trench and a rupture length of 37 km indicate a history of three latest Quaternary earthquakes with magnitudes of M 6.6-7.1 on the southern part of the Steens fault zone.

Bulletin of the Seismological Society of America↗
USGS2017

Using multi-date satellite imagery to monitor invasive grass species distribution in post-wildfire landscapes: An iterative, adaptable approach that employs open-source data and software

Among the most pressing concerns of land managers in post-wildfire landscapes are the establishment and spread of invasive species. Land managers need accurate maps of invasive species cover for targeted management post-disturbance that are easily transferable across space and time. In this study, we sought to develop an iterative, replicable methodology based on limited invasive species occurrence data, freely available remotely sensed data, and open source software to predict the distribution of Bromus tectorum (cheatgrass) in a post-wildfire landscape. We developed four species distribution models using eight spectral indices derived from five months of Landsat 8 Operational Land Imager (OLI) data in 2014. These months corresponded to both cheatgrass growing period and time of field data collection in the study area. The four models were improved using an iterative approach in which a threshold for cover was established, and all models had high sensitivity values when tested on an independent dataset. We also quantified the area at highest risk for invasion in future seasons given 2014 distribution, topographic covariates, and seed dispersal limitations. These models demonstrate the effectiveness of using derived multi-date spectral indices as proxies for species occurrence on the landscape, the importance of selecting thresholds for invasive species cover to evaluate ecological risk in species distribution models, and the applicability of Landsat 8 OLI and the Software for Assisted Habitat Modeling for targeted invasive species management.

International Journal of Applied Earth Observation↗
USGS2009

Comparison of Surface Flow Features from Lidar-Derived Digital Elevation Models with Historical Elevation and Hydrography Data for Minnehaha County, South Dakota

The U.S. Geological Survey (USGS) has taken the lead in the creation of a valuable remote sensing product by incorporating digital elevation models (DEMs) derived from Light Detection and Ranging (lidar) into the National Elevation Dataset (NED), the elevation layer of 'The National Map'. High-resolution lidar-derived DEMs provide the accuracy needed to systematically quantify and fully integrate surface flow including flow direction, flow accumulation, sinks, slope, and a dense drainage network. In 2008, 1-meter resolution lidar data were acquired in Minnehaha County, South Dakota. The acquisition was a collaborative effort between Minnehaha County, the city of Sioux Falls, and the USGS Earth Resources Observation and Science (EROS) Center. With the newly acquired lidar data, USGS scientists generated high-resolution DEMs and surface flow features. This report compares lidar-derived surface flow features in Minnehaha County to 30- and 10-meter elevation data previously incorporated in the NED and ancillary hydrography datasets. Surface flow features generated from lidar-derived DEMs are consistently integrated with elevation and are important in understanding surface-water movement to better detect surface-water runoff, flood inundation, and erosion. Many topographic and hydrologic applications will benefit from the increased availability of accurate, high-quality, and high-resolution surface-water data. The remotely sensed data provide topographic information and data integration capabilities needed for meeting current and future human and environmental needs.

Scientific Investigations Report↗